1. Field of the Invention
The present invention relates to an automatic fire protection sprinkler, and in particular an upright sprinkler having an extended body.
2. Related Art
Fire protection sprinklers conventionally are connected to a conduit to receive pressurized fire-extinguishing fluid, such as water. A typical sprinkler has a base with a threaded portion for connection to the conduit and an output orifice to output the fluid to provide fire control and/or suppression. The output orifice is sealed by a seal cap, which is held in place by a release mechanism. The release mechanism is designed to release the cap under predetermined conditions, thereby initiating the flow of fire-extinguishing fluid. A typical release mechanism includes a thermally-responsive element, e.g., a frangible bulb or fusible link, and may also include a latching mechanism.
Certain conventional sprinklers have a pair of arms that extend from the base portion and meet at a hub portion to form a frame. The hub portion is spaced apart from the output orifice of the base portion and is aligned with a longitudinal axis thereof. The hub portion may have a set-screw configured to apply a pre-tension force to the release mechanism. A deflector may be mounted on the hub, transverse to the output orifice, to provide dispersion of the output fluid.
Fire protection sprinklers may be mounted on a fluid conduit running along a ceiling and may either depend downward from the conduit, which is referred to as a “pendent” configuration, or may extend upward, which is referred to as an “upright” configuration. Upright sprinklers may be mounted on a “sprig” or “sprig-up”, which is a supply line that extends vertically from the fluid conduit to supply a single sprinkler.
A sprig may be formed by attaching a short section of pipe (referred to as a “nipple”) to a “tee” or butt-weld branch connection. A tee branch may be formed, for example, by attaching a mechanical tee to the pipe, which has a base that conforms to the pipe and a threaded or grooved portion that extends from the base. A butt-weld branches may be formed, for example, by welding a fitting to the supply pipe, such as a Weldolet® (Bonney Forge, Mount Union, Pa.), which is a forged steel fitting that conforms to the contour of the supply pipe. The sprinkler is installed in a threaded connection at the end of the sprig. In the case of a branch connection having a grooved connection, the section of pipe may be an “adapter nipple”, which is grooved at one end and a threaded port at the other end for receiving the threaded end of the sprinkler.
One of the disadvantages of the conventional sprig configuration is that it requires the use of a separate pipe section for each sprinkler, which increases the number of components in the system. This also adds to installation time, because it requires the separate steps of connecting the pipe section to the branch and connecting the sprinkler to the pipe section. This configuration also increases the probability of leakage, because it doubles the number of connections between the sprinklers and the conduits (i.e., it requires two connections per sprinkler). Furthermore, conventional upright sprinkler bodies are not configured to accommodate a grooved connection without an adapter.
Sprinklers generally may be categorized as “control mode” or “suppression mode”. Control mode sprinklers are designed to limit the size of a fire by distribution of water, so as to decrease the heat release rate and pre-wet adjacent combustibles, while controlling ceiling gas temperatures to avoid structural damage. Suppression mode sprinklers are designed to sharply reduce the heat release rate of a fire and prevent its regrowth by means of direct and sufficient application of water through the fire plume to the burning fuel surface.
The thermal sensitivity of a sprinkler is a measure of the rapidity with which thermally-responsive release mechanism operates as installed in a specific sprinkler or sprinkler assembly. One measure of thermal sensitivity is the response time index (RTI) as measured under standardized test conditions. Sprinklers defined as fast response have a thermal element with an RTI of 50 m-s1/2 or less. Sprinklers defined as standard response have a thermal element with an RTI of 80 m-s1/2 or more.
“Specific application control mode storage” sprinklers, as defined in UL 199 (“Standard for Automatic Sprinklers for Fire-Protection Service,” Underwriters' Laboratories, 11th Ed., Nov. 4, 2005), are designed for the protection of stored commodities, as specified in NFPA 13 (“Standard for the Installation of Sprinkler Systems,” National Fire Protection Association, Inc., 2002 Edition), or particular end use limitations specified for the sprinkler (e.g., specific hazards or construction features). According to Section 3.6.2.12 of NFPA 13, a specific application control mode sprinkler (for storage use) is a type of spray sprinkler listed at a minimum operating pressure with a specific number of operating sprinklers for a given protection scheme. Such sprinklers may be used to protect storage of Class I through Class IV commodities, plastic commodities, miscellaneous storage, and other storage as specified in Chapter 12 of NFPA 13 (see Section 12.1.2.3).
Sections 8.5 and 8.6 of NFPA 13 specify requirements for the installation of standard pendent and upright sprinklers. In particular, Section 8.6.5.2.1.3 specifies requirements for the spacing of standard upright sprinklers with respect to obstructions that may interfere with the sprinkler spray pattern. However, as indicated in Section 8.6.5.2.1.8, these spacing requirements do not apply to upright sprinklers that are directly attached, i.e., attached without a sprig-up, to a supply pipe having a diameter of less than 3 inches. Thus, sprinklers that are designed to be installed without sprig-ups have the advantage of less stringent spacing requirements.
Sections 8.5 and 8.11 specify requirements for the installation of special application control mode sprinklers for storage applications. Section 8.11.5 specifies requirements for installation of special application control mode sprinklers near obstructions that may interfere with the sprinkler spray pattern. Section 8.11.5.2.2 states that sprinklers are permitted to be attached directly to branch lines less than 2 inches in diameter. Sprinklers may be directly attached to larger diameter branch lines, as well. However, certain minimum distances apply to the use of sprig-ups (or “riser nipples”). Specifically, sprinklers supplied by a riser nipple must elevate the sprinkler deflector a minimum of 13 inches from the centerline of a 2.5 inch pipe and a minimum of 15 inches from the centerline of a 3 inch pipe. Thus, sprinklers that are designed to be installed without sprig-ups have the advantage of allowing more flexibility in installation.